This invention relates to communication between two or more devices positioned at a distance from each other, where power consumption is a limiting factor.
One example where this can occur would be transmitting data gathered by a battery-powered sensor that is implanted within the human body to the outside world over a long period of time. In this example, especially when continuous monitoring and transmission is being made of physiological, chemical or physical parameters, the battery power may not be sufficient for the transmission to continue for a sufficiently long time when data transmission is implemented using conventional techniques. As a result, the battery may require replacement by an invasive procedure.
Another example is when data or instructions/commands are to be transmitted from one point within a body to a second point in the same body. For example, it may be desirable to have a sensor that measures pulmonary vein blood pressure transmitted pressure data to a cardiac pacemaker in order to optimize the pacemaker's performance. Once again, battery power may not be sufficient and the battery may require replacement by an invasive procedure.    Examples of using ultrasound to detect an implanted device are described in Detection of Deeply Implanted Impedance-Switching Devices Using Ultrasound Doppler by J. M Mari et al, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 60, no. 6, June 2013, at 1074-1083. This article is incorporated herein by reference in its entirety.    Examples of using ultrasound to communicate with an implanted device are described in Deeply Implanted Medical Device Based on a Novel Ultrasonic Telemetry Technology by Michela Peisino, Thèse no 5730, École Polytechnique Fédérale de Lausanne, May 17, 2013. This paper is incorporated herein by reference in its entirety.    Examples of using ultrasound for energy transfer and communication with implanted devices are described in Ultrasound for Wireless Energy Transfer and Communication for Implanted Medical Devices by F. Mazzilli and C. Dehollain, ESSCIRC 2010, Workshop, Seville, Sep. 17, 2010. This paper is incorporated herein by reference in its entirety.
But the impedance-switching based technology described in these references is inadequate, and improved approaches for communicating with implanted devices are needed.